Semiconductor light emitting element and method of making the same

ABSTRACT

A semiconductor light-emitting element  10  includes a silicon single crystal substrate  20  having a first and a second surfaces  20   a   , 20   b  in head-tail relationship with each other, a GaN-based semiconductor laminate  40  formed on a selected region of the first surface with a predetermined conductive intermediate layer  25  interposed therebetween, a first electrode layer  51  having a portion in contact with an uppermost layer of the GaN-based semiconductor laminate  40  and insulated from the monocrystal silicon substrate, and a second electrode layer  52  formed on a suitable portion of the monocrystal silicon substrate. The monocrystal silicon substrate  20  is formed with a light guide  30  for directing light emitted from the GaN-based semiconductor laminate  40  toward the second surface  20   b.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a semiconductor GaN-based lightemitting element containing gallium nitride and to a method of makingthe same.

2. Description of the Related Art

A semiconductor light-emitting element (a blue-color light-emittingdiode) for blue-color light emission has been developed and put topractical use. It has a sapphire substrate on which a compoundsemiconductor crystal containing gallium nitride (GaN) is epitaxiallygrown by vapor-phase growth of an organic metal compound. Since sapphirediffers only slightly in lattice constant from a GaN-based semiconductorcrystal, it provides a suitable surface for epitaxially growing aGaN-based compound semiconductor layer while succeeding the crystalorientation of the sapphire.

However, since sapphire is expensive and has poor processability, aconventional diode for blue-color light emission fabricated with use ofsuch a substrate is inevitably expensive.

On the other hand, JP-A-2000-31534 for example discloses a techniqueutilizing a silicon single crystal substrate as an inexpensive andreadily processible substrate for making a blue-color light-emittingdiode. According to this technique, a monocrystal silicon substrate issurface-treated with hydrogen and then formed with a titanium nitridelayer as an intermediate layer for growth of a GaN-based semiconductor.Such hydrogen surface treatment makes hydrogen joined to dangling bondson the surface of the silicon substrate, which prevents formation oftitanium silicide which is an amorphous layer. Further, since titaniumnitride has a cubic crystal structure similarly to silicon, titaniumnitride can be appropriately grown on the silicon substrate whilesucceeding the crystal orientation of silicon. Further, by properlysetting the thickness of the TiN layer, the GaN-based compoundsemiconductor layers subsequently formed thereon also succeed thecrystal orientation of silicon.

In place of forming an intermediate layer of TiN as described above, theabove document also proposes another method which utilizes anintermediate layer made of AlN/AlCaN for forming a blue-light-emittingdiode by epitaxial growth of a GaN-based semiconductor on a monocrystalsilicon substrate.

However, since silicon is a light-absorptive material as is generallyknown, the blue-color light-emitting diode disclosed in the abovedocument still has room for improvement in light-emitting efficiency.

To improve light-emitting efficiency, JP-A-5-13816 for example proposesa technique which takes advantage of transparency of a sapphiresubstrate for emitting light from the sapphire substrate.

However, since sapphire is expensive and has a poor processability asdescribed above, a blue-color light-emitting diode fabricated with useof a sapphire substrate is still expensive. Further, it is desirable tomake the chip as small as possible in view of the high cost of thesubstrate while also increasing the current density passing through theactivation layer. Then, some practical and useful way must be sought forproperly mounting such a compact chip on a mother substrate or framewhile maintaining the light-emitting efficiency.

SUMMARY OF THE INVENTION

The present invention has been proposed under the circumstancesdescribed above. It is, therefore, an object of the present invention toprovide a semiconductor light-emitting element which is less costly butyet provides enhanced light-emitting efficiency.

It is another object of the present invention to provide a semiconductorlight-emitting element which can be easily mounted on a carrier whileproviding good light-emitting efficiency.

To fulfill the above-mentioned objects, the present invention employsthe following technical measures.

A semiconductor light-emitting element according to a first aspect ofthe present invention comprises a silicon single crystal substratehaving a first and a second surfaces in head-tail relationship with eachother, a GaN-based semiconductor laminate formed on a selected region ofthe first surface with a predetermined conductive intermediate layerinterposed therebetween, a first electrode layer having a portion incontact with an uppermost layer of the GaN-based semiconductor laminateand insulated from the monocrystal silicon substrate, and a secondelectrode layer formed on a suitable portion of the monocrystal siliconsubstrate. The monocrystal silicon substrate is formed with a lightguide for directing light emitted from the GaN-based semiconductorlaminate toward the second surface.

According to a preferred embodiment, the light guide comprises a holepenetrating the monocrystal silicon substrate thicknesswise, and theGaN-based semiconductor laminate includes a lowermost layer whosesurface includes a portion substantially exposed to the second surface.

In this case, the hole may be preferably filled with translucent resin.Further, the resin may preferably contain a fluorescent or lightscattering material.

In the preferred embodiment, the hole flares to have increasing diametertoward the second surface. Alternatively, the hole may be parabolic tohave increasing diameter toward the second surface.

In the preferred embodiment, the uppermost layer of the GaN-basedsemiconductor laminate is covered with a insulating layer excepting apredetermined center region contacting the first electrode layer.

In the preferred embodiment, the center region has a diameter smallerthan that of the hole formed with the monocrystal silicon substrate.

In the preferred embodiment, the selected region is provided in adepression of the first surface. The depression may be preferably filledwith a protective member. Further, the protective member may bepreferably heat-conductive.

According to another preferred embodiment, the GaN-based semiconductorlaminate has a portion positioned offset thicknesswise relative to theother portion.

According to a further preferred embodiment, the first surface of themonocrystal silicon substrate is formed with another electronic element.

Preferably, the first and the second electrode layers may be arranged onthe first surface side of the monocrystal silicon substrate.

A second aspect of the present invention provides a mounting structureof a semiconductor light-emitting element which is characterized thatthe semiconductor light-emitting element according to the first aspectis mounted on a carrier with the first surface directed downward.

A third aspect of the present invention provides a method ofmanufacturing a semiconductor light-emitting element, which ischaracterized by the following steps.

(a) A step of forming a GaN-based semiconductor laminate on a selectedregion of a first surface of a monocrystal silicon substrate with apredetermined conductive intermediate layer interposed therebetween. Themonocrystal silicon substrate also having a second surface in head-tailrelationship with the first surface.

(b) A step of forming a first electrode layer and a second electrodelayer. The first electrode layer has a portion in contact with anuppermost layer of the GaN-based semiconductor laminate and is insulatedfrom the monocrystal silicon substrate. The second electrode layer isformed on a suitable portion of the monocrystal silicon substrate.

(c) A step of forming a light guide in the monocrystal silicon substratefor directing light emitted from the GaN-based semiconductor laminatetoward the second surface.

A fourth aspect of the present invention provides a semiconductorlight-emitting element which comprises a monocrystal silicon substratehaving a first and a second surfaces in head-tail relationship with eachother, and a light-emitting diode chip mounted on a selected region ofthe first surface. The monocrystal silicon substrate is formed with alight guide for directing light emitted from the light-emitting diodechip toward the second surface.

According to a preferred embodiment, the light-emitting diode chip is ablue-color light-emitting diode chip formed by growing a GaN-basedsemiconductor laminate on a sapphire substrate.

In this case, the blue-color light-emitting diode chip may be mounted onthe selected region with the sapphire substrate directed downward.Alternatively, the blue-color light-emitting diode chip may be mountedon the selected region with the sapphire substrate directed upward.

In the preferred embodiment, the light guide comprises a holepenetrating the monocrystal silicon substrate thicknesswise with aportion of the light-emitting diode chip substantially exposed to thesecond surface side.

In the preferred embodiment, the hole may be preferably filled withtranslucent resin. Further, the resin may preferably contain afluorescent or light scattering material.

In the preferred embodiment, the hole flares to have increasing diametertoward the second surface. Alternatively, the hole may be parabolic tohave increasing diameter toward the second surface.

In the preferred embodiment, the selected region is provided in adepression of the first surface. In this case, the depression may bepreferably filled with a protective member.

In another preferred embodiment, the first surface of the monocrystalsilicon substrate is formed with another electronic element.

Preferably, the first surface of the monocrystal silicon substrate maybe provided with a first electrode layer connected to an electrode ofthe blue-color light-emitting diode chip, and a second electrode layerconnected to another electrode of the blue-color light-emitting diodechip.

A fifth aspect of the present invention provides amounting structure ofa semiconductor light-emitting element, wherein the semiconductorlight-emitting element according to the fourth aspect of the presentinvention is mounted on a carrier with the first surface facingdownward.

Other features and advantages of the present invention will becomeclearer from the detailed description of the preferred embodiments givenbelow with reference to the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a vertical sectional view a semiconductor light-emittingelement according to showing a first embodiment of the presentinvention, whereas FIG. 1B is a vertical sectional view showing asemiconductor light-emitting element according to a modification of thefirst embodiment of the present invention;

FIG. 2 is an enlarged sectional view of a principal part of thesemiconductor light-emitting element shown in FIG. 1A;

FIGS. 3A-3E show an example of method of making the semiconductorlight-emitting element shown in FIG. 1A;

FIG. 4 shows the semiconductor light-emitting element of FIG. 1A in amounted condition;

FIG. 5 is a sectional view showing a principal part of a semiconductorlight-emitting element according to a second embodiment of the presentinvention;

FIG. 6 is a sectional view showing a principal part of a semiconductorlight-emitting element according to a third embodiment of the presentinvention.

FIG. 7 is a sectional view showing a principal part of a semiconductorlight-emitting element according to a fourth embodiment of the presentinvention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Preferred embodiments of the present invention will be described belowin detail with reference to the accompanying drawings. FIG. 1A is a viewof a semiconductor light-emitting element 10, in vertical section,according to a first embodiment of the present invention, FIG. 1B is aview of a modification of the first embodiment, in vertical section,FIG. 2 is an enlarged view showing a principal part of FIG. 1A, andFIGS. 3A-3E show an example of process for making the semiconductorlight-emitting element shown in FIG. 1A.

As shown in FIGS. 1A and 2, the semiconductor light-emitting element 10includes a monocrystal silicon substrate 20 of a predetermined thicknesshaving an upper or first surface 20A and a lower or second surface 20B.The monocrystal silicon substrate 20 is rectanglar in plan view forexample. The upper surface of the monocrystal silicon substrate 20 has aselected center region formed with a depression 21 of a predetermineddepth. The depression 21 is circular in plan view for example.

The monocrystal silicon substrate 20 is formed with a thorough-hole 31extending thicknesswise from the bottom of the depression 21 to thesecond surface 20 b. The through-hole 31 preferably flares to haveincreasing diameter toward the second surface 20 b.

The depression 21 is provided with a GaN-based semiconductor laminate 40riding on a peripheral mouth portion 31 a of the hole 31. Morespecifically, as clearly shown in FIG. 2, the GaN-based semiconductorlaminate 40 includes for example an N-type semiconductor layer 41 (GaNlayer or AlGaN layer), an activation layer 42 (InGaN layer), and aP-type semiconductor layer 43 (GaN layer of AlGaN layer). These layersare successively formed by epitaxial growth. To realize appropriategrowth of the GaN-based semiconductor laminate 40 on the monocrystalsilicon substrate 20, an intermediate layer 25 of e.g. titanium nitride(TiN) is first formed on the monocrystal silicon substrate 20 before thegrowth of and then the GaN-based semiconductor laminate 40. A method offorming the GaN-based semiconductor laminate 40 will be described laterwith reference to FIGS. 3A-3E.

The uppermost layer of the GaN-based semiconductor laminate 40 has asurface held in contact with a part of a first electrode layer 51. Thefirst electrode layer 51 is insulated from the monocrystal siliconsubstrate 20. More specifically, the first surface 20 a of themonocrystal silicon substrate 20 is formed with an insulating layer 61of e.g. SiO2 by vacuum spattering or vapor deposition optionallycombined with etching. The insulating layer covers the uppermost layerof the GaN-based semiconductor laminate 40 other than a predeterminedcenter region while also covering a region from the depression 21 to thefirst surface 20 a where the first electrode layer 51 extends. The firstelectrode layer 51 is formed by vacuum spattering or vapor deposition ofan Au- or Ag-based conductive metal optionally combined with etching. Inthe illustrated embodiment, first electrode layer 51 has one endcontacting the upper surface of the GaN-based semiconductor laminate 40at the inside of the depression 21, whereas the other end is positionedat a suitable portion over the first surface 20 a of the monocrystalsilicon substrate 20. The insulating layer 61 has a mouth 61 a, which isdiamatically smaller than the mouth 31 a of the hole 31 on the firstsurface 20 a of the monocrystal silicon substrate 20 for exposing theupper surface of the semiconductor laminate 40. The first surface 20 aof the monocrystal silicon substrate 20 also has a suitably selectedportion formed with a second electrode layer 52 electrically connectedto the monocrystal silicon substrate 20. The second electrode layer 52may be formed in the same manner as the first electrode layer 51.

The depression 21 is filled with a protective member 62 of e.g. epoxyresin for partially burying the first electrode layer 51. The protectivemember 62 preferably contains a good heat-conductive material such as asilicon for adjusting heat dissipation.

The hole 31 is preferably filled with a translucent resin 32 such asepoxy resin. The epoxy resin serves as a light guide 30 for guidinglight emitted from the GaN-based semiconductor laminate 40 toward fromthe second surface 20 b side while also serving as a protective memberfor the semiconductor laminate 40. The epoxy resin may be contain alight scattering material such as fluorescent or metalic particles.

With the structure described above, the P-type semiconductor layer 43 ofthe GaN-based semiconductor laminate 40 is connected to the firstelectrode layer 51, whereas the N-type semiconductor layer 41 isconnected to the second electrode layer 52 via the monocrystal siliconsubstrate 20. Consequently, voltage application across the electrodelayers 51 and 52 causes the activator 42 of the GaN-based semiconductorlaminate 40 to emit blue-light. The light can be efficiently let outbeyond the second surface 20 b of the monocrystal silicon substrate 20via the light guide 30. As described above, when the light guide 30(epoxy resin 32) contains a fluorescent or light scattering material,light can be adjusted emitted efficiently from the entire mouth of thelight guide 30 beyond the second surface 20 while also providing apossibility for color adjustment. Further, in the illustratedembodiment, the exposed portion of the GaN-based semiconductor laminate40 at the first surface 20 a side is completely covered with a metalelectrode layer (the first electrode layer 51). Consequently, the metalelectrode layer serves as a reflector for efficiently reflecting light,traveling from the activation layer 42 upward in FIG. 1A, toward thelight guide 30, which also results in significant improvement inlight-emitting efficiency. Further, the mouth 61 a of the insulatinglayer 61 covering the GaN-based semiconductor laminate 40 at the firstsurface 20 a has is diametrically smaller than the light guide 30.Consequently, the activation layer 42 can emit light primarily from theselected center region. Thus, the light-emitting portion can beprevented from being shaded behind the edge 31 a of the hole 31 of themonocrystal silicon substrate 20, which also contributes to improvementof light-emitting efficiency.

In addition, the substrate of the semiconductor light-emitting element10 is made of monocrystal silicon. Consequently, as shown in FIG. 1B,wafer process maybe performed on the first surface 20 a of the substrate20 to form another element or a set of elements 90 such as a currentregulating drive circuit or a logic circuit as a part of an IC-built-insemiconductor light-emitting element, or to form a discrete element suchas a diode, or sensor or the like.

FIG. 4 shows an example of mounting structure wherein the semiconductorlight-emitting element 10 having the above-described arrangement ismounted on a carrier such as a mother board 5. Since the first electrodelayer 51 and the second electrode layer 52 are formed on the firstsurface 20 a of the monocrystal silicon substrate 20, the semiconductorlight-emitting element 10 can be mounted in face-down relation onto themother substrate 5. In such a mounting structure, light emitted from theGaN-based semiconductor laminate 40 advantageously goes out upward viathe light guide 30.

Next, reference is made to FIGS. 3A-3E for describing an example ofprocess of making the semiconductor light-emitting element 10 having theabove-described structure.

As shown in FIG. 3A, a monocrystal silicon substrate 20 is prepared. Themonocrystal silicon substrate 20 has a thickness of 200-400 μm andincludes a first and a second surfaces 20 a, 20 b in head-tailrelationship. The figure shows a devided region only for an individualsemiconductor light-emitting element which is rectangular in top view.In actual production, use may be made of a wafer which corresponds to aplurality of such regions arranged vertically and horizontally. Thefirst surface 20 a has a depression 21 formed by etching for example.The depression 21 is circular for example in top view.

The depression 21 on the first surface 20 a of the Monocrystal siliconsubstrate 20 is formed with a GaN-based semiconductor laminate 40. Toform properly such a semiconductor laminate 40, the monocrystal siliconsubstrate 20 is hydrogen-terminated follower by forming an intermediatelayer 25 of titanium nitride (TiN) by plasma spattering for example.Subsequently, the GaN-based semiconductor laminate 40 is formed on theintermediate layer by epitaxial growth. More specifically, the GaN-basedsemiconductor laminate 40 is formed by successive epitaxial growth of anN-type semiconductor layer 41 (GaN layer or AlGaN layer), an activationlayer 42 (InGaN layer), and a P-type semiconductor layer 43 (GaN layeror AlGaN layer). To limit the area of the GaN-based semiconductorlaminate 40 to the region of the depression 21, the semiconductorlaminate 40 may be firstly grown on the whole area of the first surface20 a of the monocrystal silicon substrate 20, followed by etching awayan excessive portion. Alternatively, the semiconductor laminate 40 maybe formed by selective epitaxial growth for limitting the growth region.When the monocrystal silicon substrate is Hydrogen-terminated and thenformed with a TiN intermediate layer, a GaN-based semiconductor laminatecan be properly grown thereon, as previously mentioned at the beginningof this specification.

Next, as shown in FIG. 3C, a predetermined portion of the first surface20 a of the monocrystal silicon substrate 20 is formed with aninsulating layer 61 of a silicon oxide layer (SiO2) for example as byvapor deposition, spattering or the like. The insulating layer 61 coversthe depression 21 except for the central portion of the upper surface ofthe GaN-based semiconductor laminate 40 and extends to a suitableportion of the first surface 20 a. The coverage area of the insulatinglayer 61 may be selected by etching.

Next, as shown in FIG. 3D, a first and a second electrode layers 51 and52 are formed. As described above, the first electrode layer 51 isformed in contact with the exposed portion of the upper surface of theGaN-based semiconductor laminate 40 and extends to a suitable positionon the first surface 20 a. The second electrode layer 52 is directlyformed on an appropriate portion of the first surface 20 a of themonocrystal silicon substrate 20. The first and second electrode layers51, 52 are formed by vapor deposition or spattering, and their coverageareas are selected by etching. The electrode layers 51, 52 are made ofan Au- or Ag-based metal material for example.

Next, as shown in FIG. 3E, the monocrystal silicon substrate 20 isformed with a hole 31 extending from the second surface 20 b topartially expose the bottom surface of the GaN-based semiconductorlaminate 40. The hole 31 may be formed by etching for example.

Next, the depression 21 of the first surface 20 a is filled with aprotective member 62, and the hole 31 is filled with translucent resin32 such as epoxy resin. Then, the wafer is divided into unit elementsfor providing the semiconductor light-emitting elements 10 each havingthe structure shown in FIG. 1A.

FIG. 5 is a sectional view showing a principal part of a semiconductorlight-emitting element 10 according to a second embodiment of thepresent invention. This embodiment differs from the embodiment shown inFIG. 1A in the following respects. A GaN-based semiconductor laminate 40includes a central region positioned offset toward a first surface 20 aof a monocrystal silicon substrate 20 relative to a peripheral region. Ahole 31 formed in the monocrystal silicon substrate 20 is parabolic withits diameter increasing toward the second surface 20 b. Further, thehole 31 has an inner surface provided with a reflector 33 formed byvapor deposition of Ag or Al for example. The structure is otherwise thesame as in the embodiment shown in FIG. 1A, and is not furtherdescribed.

Since the GaN-based semiconductor laminate 40 is partially offset asdescribed above, the surface of the semiconductor laminate 40 is bent.Since the GaN-based semiconductor laminate 40 has a reflective index ofno less than 2, light emitted from the activation layer 42 encountersdifficulty in going out. However, the bent surface of the semiconductorlayer 40 increases the possibility that the light traveling within thesemiconductor laminate 40 strikes into the surface at an angle smallerthan the critical reflection angle, which assists the light to go out.This contributes to improvement in the light-emitting efficiency of thesemiconductor light-emitting element 10.

Further, since the inner surface of hole 31 is parabolic inner surfaceas described above with the reflector 33 formed thereon, light can beefficiently emitted outside. It is easily understood that thesemiconductor light-emitting element 10 according to this embodiment canbe fabricated in the same manner as described above with reference toFIGS. 3A-3E.

FIG. 6 is a sectional view showing a semiconductor light-emittingelement 10 according to a third embodiment of the present invention. Thesemiconductor light-emitting element 10 has a monocrystal siliconsubstrate 20 including a first and a second surfaces 20 a, 20 b. Thefirst surface 20 a is provided with a blue-color light-emitting diodechip 70 fabricated in a conventional manner. Light emitted from theblue-color light-emitting diode chip 70 goes out from the second surface20 b of the substrate 20 via a light guide 30 penetrating themonocrystal silicon substrate 20.

The blue-color light-emitting diode chip 70 fabricated in theconventional manner has a sapphire substrate 71 including an uppersurface successively formed with an N-type semiconductor layer 72 (GaNlayer or AlGaN layer), an activation layer 73 (InGaN layer), and aP-type semiconductor layer 74 (GaN layer or AlGaN layer). The N-typesemiconductor layer 72 has an exposed portion formed with an N-sideelectrode 52, whereas the P-type semiconductor layer 74 includes asurface formed with a P-side electrode 51. In this embodiment, the chipis mounted on a depression 21 formed on the first surface 20 a with thesapphire substrate 71 positioned below. Each of the N-side electrode 52and the P-side electrode 51 is connected, by wire bonding, to acorresponding wiring pattern 80 arranged on the first surface 20 a.Wiring patterns 80 corresponding to the N-side electrode 52 and theP-side electrode 54 extend to suitable portions on the first surface 20a where bumps 63 are formed. Each wiring pattern 80 has a lower surfaceformed with an insulating layer 61 made of e.g. silicon oxide film forinsulation from the monocrystal silicon substrate 20.

As in the first embodiment, the hole 31 formed in the monocrystalsilicon substrate 20 is preferably filled with translucent resin 32 suchas epoxy resin. The depression 21 on the first surface 20 a is alsofilled with a protective member 62 such as epoxy resin to protect thechip 70 and the bonding wires 75.

In the structure described above, light emitted from the activationlayer 73 of the light-emitting diode chip 70 travels via the transparentsapphire substrate 71 and the light guide 30 to go out efficiently fromthe second surface 20 b. The P-side electrode 51 which is a full-surfaceelectrode functions as a reflector. Thus, light emitted from theactivation layer 73 upward in FIG. 6 is reflected toward the light guide30 to go out from the second surface 20 b of the substrate 20efficiently without being wasted.

In this embodiment, similarly to the first embodiment, the monocrystalsilicon substrate 20 may be formed integrally with a current regulatingdrive circuit or a logic circuit by wafer process. The semiconductorlight-emitting element may be mounted on a carrier such as a mothersubstrate 5 with the first surface 20 a of the substrate 20 directeddown.

FIG. 7 is a sectional view showing a semiconductor light-emittingelement 10 according to a fourth embodiment of the present invention.This embodiment, as in the embodiment shown in FIG. 6, utilizes ablue-color light-emitting diode chip 70 fabricated in a conventionalmanner. However, the chip is mounted on a sapphire substrate 71positioned above. In this case, an N-side electrode 52 and a P-sideelectrode 51 are adjusted in height, and each of the electrodes 51, 52is connected directly to a respective wiring pattern 80 via ananisotropic conductive layer or a conductive adhesive. The structure isotherwise the same as in the embodiment shown in FIG. 6, and is notfurther described. It may be easily understood that this embodimentenjoys the same benefits as the embodiment shown in FIG. 6. In addition,in this embodiment, when the surface of the sapphire substrate 71 isformed with a metal reflector (not shown), light traveling from theactivation layer 73 upward in the figure is reflected toward the lightguide 30, which enhances light-emitting efficiency of the semiconductorlight-emitting element 10.

The present invention is not limited to the specific embodimentsdescribed above. All variations covered by the following claims areintended to be included in the scope of the present invention.

For instance, the intermediate layer 25 for proper growth of theGaN-based semiconductor laminate 40 on the monocrystal silicon substrate20 may be made of AlN/AlGaN instead of TiN.

1. A semiconductor light-emitting element comprising: a silicon singlecrystal substrate having a first and a second surfaces in head-tailrelationship with each other; a GaN-based semiconductor laminate formedon a selected region of the first surface with a predeterminedconductive intermediate layer interposed therebetween; a first electrodelayer having a portion in contact with an uppermost layer of theGaN-based semiconductor laminate and insulated from the monocrystalsilicon substrate; and a second electrode layer formed on a suitableportion of the monocrystal silicon substrate; wherein the monocrystalsilicon substrate is formed with a light guide for directing lightemitted from the GaN-based semiconductor laminate toward the secondsurface.
 2. The semiconductor light-emitting element according to claim1, wherein the light guide comprises a hole penetrating the monocrystalsilicon substrate thicknesswise, the GaN-based semiconductor laminateincluding a lowermost layer whose surface includes a portionsubstantially exposed to the second surface.
 3. The semiconductorlight-emitting element according to claim 2, wherein the hole is filledwith translucent resin.
 4. The semiconductor light-emitting elementaccording to claim 3, wherein the resin contains a fluorescent or lightscattering material.
 5. The semiconductor light-emitting elementaccording to claim 2, wherein the hole flares to have increasingdiameter toward the second surface.
 6. The semiconductor light-emittingelement according to claim 2, wherein the hole is parabolic to haveincreasing diameter toward the second surface.
 7. The semiconductorlight-emitting element according to claim 1, wherein the uppermost layerof the GaN-based semiconductor laminate is covered with a insulatinglayer excepting a predetermined center region contacting the firstelectrode layer.
 8. The semiconductor light-emitting element accordingto claim 7, wherein the center region has a diameter smaller than thatof the hole formed with the monocrystal silicon substrate.
 9. Thesemiconductor light-emitting element according to claim 1, wherein theselected region is provided in a depression of the first surface. 10.The semiconductor light-emitting element according to claim 9, whereinthe depression is filled with a protective member.
 11. The semiconductorlight-emitting element according to claim 10, wherein the protectivemember is heat-conductive.
 12. The semiconductor light-emitting elementaccording to claim 1, wherein the GaN-based semiconductor laminate has aportion positioned offset thicknesswise relative to the other portion.13. The semiconductor light-emitting element according to claim 1,wherein the first surface of the monocrystal silicon substrate is formedwith another electronic element.
 14. The semiconductor light-emittingelement according to claim 1, wherein the first and the second electrodelayers are arranged on the first surface side of the monocrystal siliconsubstrate.
 15. A mounting structure of a semiconductor light-emittingelement comprising: a monocrystal silicon substrate having a first and asecond surfaces in head-tail relationship with each other; a GaN-basedsemiconductor laminate formed on a selected region of the first surfacewith a predetermined conductive intermediate layer interposedtherebetween; a first electrode layer having a portion in contact withan uppermost layer of the GaN-based semiconductor laminate and insulatedfrom the monocrystal silicon substrate, the first electrode beingarranged on the first surface side of the monocrystal silicon substrate;and a second electrode layer arranged on the first surface side of themonocrystal silicon substrate; wherein the monocrystal silicon substrateis formed with a light guide for directing light emitted from theGaN-based semiconductor laminate toward the second surface, wherein themonocrystal silicon substrate is mounted on a carrier via the first andthe second electrode layers.
 16. A semiconductor light-emitting elementcomprising: a monocrystal silicon substrate having a first and a secondsurfaces in head-tail relationship with each other; and a light-emittingdiode chip mounted on a selected region of the first surface; whereinthe monocrystal silicon substrate is formed with a light guide fordirecting light emitted from the light-emitting diode chip toward thesecond surface.
 17. The semiconductor light-emitting element accordingto claim 16, wherein the light-emitting diode chip is a blue-colorlight-emitting diode chip formed by growing a GaN-based semiconductorlaminate on a sapphire substrate.
 18. The semiconductor light-emittingelement according to claim 17, wherein the blue-color light-emittingdiode chip is mounted on the selected region with the sapphire substratedirected downward.
 19. The semiconductor light-emitting elementaccording to claim 18, wherein the blue-color light-emitting diode chipis mounted on the selected region with the sapphire substrate directedupward.
 20. The semiconductor light-emitting element according to claim16, wherein the light guide comprises a hole penetrating the monocrystalsilicon substrate thicknesswise with a portion of the light-emittingdiode chip substantially exposed to the second surface side.
 21. Thesemiconductor light-emitting element according to claim 20, wherein thehole is filled with translucent resin.
 22. The semiconductorlight-emitting element according to claim 20, wherein the resin containsa fluorescent or light scattering material.
 23. The semiconductorlight-emitting element according to claim 16, wherein the hole flares tohave increasing diameter toward the second surface.
 24. Thesemiconductor light-emitting element according to claim 16, wherein thehole is parabolic to have increasing diameter toward the second surface.25. The semiconductor light-emitting element according to claim 16,wherein the selected region is provided in a depression of the firstsurface.
 26. The semiconductor light-emitting element according to claim25, wherein the depression is filled with a protective member.
 27. Thesemiconductor light-emitting element according to claim 16, wherein thefirst surface of the monocrystal silicon substrate is formed withanother electronic element.
 28. The semiconductor light-emitting elementaccording to claim 16, wherein the first surface of the monocrystalsilicon substrate is provided with a first electrode layer connected toan electrode of the blue-color light-emitting diode chip, the firstsurface being also provided with a second electrode layer connected toanother electrode of the blue-color light-emitting diode chip.
 29. Amounting structure of a semiconductor light-emitting element comprising:a monocrystal silicon substrate having a first and a second surfaces inhead-tail relationship with each other; and a light-emitting diode chipmounted on a selected region of the first surface; wherein themonocrystal silicon substrate is formed with a light guide for directinglight emitted from the light-emitting diode chip toward the secondsurface; the first surface of the monocrystal silicon substrate beingprovided with a first electrode layer connected to an electrode of theblue-color light-emitting diode chip, the first surface being alsoprovided with a second electrode layer connected to another electrode ofthe blue-color light-emitting diode chip, the light-emitting diode chipbeing mounted on a carrier via the first and the second electrodelayers.